Olefin (co)polymerization, for example ethylene (co)polymerization, typically operates at a temperature that is close to the softening temperature of the resultant (co)polymer. Insufficient heat removal can easily lead to temperature exceeding the softening temperature and cause (co)polymer agglomeration that may disrupt production continuity.
In a gas phase polymerization process, the polymerization reactor is cooled by the circulating monomer gasses to maintain a steady operating temperature. However, if the temperature of a growing resin particle approaches the sticking/melting point of the resin, resin sheeting on the reactor walls may occur. Growing resin particles are especially susceptible to overheating if they accumulate at the reactor walls, thereby losing heat-transfer with the circulating monomer gasses, and remaining in close contact with respect to each other. In such instances, particle-particle fusion may occur, followed by reactor sheeting, which, in turn, could cause reactor shutdown.
The currently available catalyst systems fail to address such heat removal concerns in olefin polymerization processes such as ethylene polymerization systems. Therefore, there is a need for a catalyst system having an effective mechanism that substantially reduces catalyst activity within a narrow temperature range and therefore reducing heat generation when the temperature in various parts of the reactor system approaches (co)polymer softening temperature to prevent agglomeration formation and minimizing production disruptions.